In traditional two-dimensional printing, ink is printed on a paper so as to form a two-dimensional pattern. Recently, three-dimensional printing, also known as additive manufacturing, is researched and developed widely and deeply. In an additive manufacturing technology, a three-dimensional image is sliced into a plurality of two-dimensional images by a computer, and a laser beam is used to weld material powder layer by layer respectively according to the data of the two-dimensional images, so as to form a three-dimensional object.
In a selective laser melting process, the variation of melt pool affects the yield of a printed three-dimensional product. For three dimensional parts, the border conditions of the conductive heat transport have a large influence on the melt pool dimensions, e.g. the shape and size. If the welded structure is suspended, the shape and the temperature distribution of the melt pool irradiated by a laser beam over the suspended welded structure are different from those over a non-suspended welded structure due to different heat dissipation conditions. In this case, if the power of the laser beam is maintained the same as the power for the non-suspended welded structure, the shape of the final welded three-dimensional object will not be satisfactory.